<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        * {
            margin: 0;
            padding: 0;
        }

        .watch {
            width: 350px;
            height: 200px;
            margin: 100px auto;
        }

        span {
            display: inline-block;
            width: 100px;
            height: 150px;
            margin: 0 5px;
            background-color: #000;
            color: white;
            font-size: 60px;
            line-height: 150px;
            font-weight: 700;
            text-align: center;
        }
    </style>

</head>

<body>
    <div class="watch">
        <span>00</span>
        <span>00</span>
        <span>00</span>
    </div>

</body>
<script>
    var timme = document.querySelectorAll('span');
    var timer1 = window.setInterval(fn, 1000);
    function fn() {
        // console.log('+1');
        var s = Number(timme[2].innerHTML) + 1;
        var m = Number(timme[1].innerHTML);
        var h = Number(timme[0].innerHTML);
        // console.log(Number(s) + 1);

        if (s == 60) {
            m = m + 1;
            s = 0;
        }
        if (m == 60) {
            h = h + 1;
            m = 0;
        }
        s = s < 10 ? '0' + s : s;
        m = m < 10 ? '0' + m : m;
        h = h < 10 ? '0' + h : h;
        timme[2].innerHTML = s;
        timme[1].innerHTML = m;
        timme[0].innerHTML = h;
    }

</script>

</html>